Medical electrical leads or drug delivery catheters (hereafter referred to as therapy devices) are placed in the contact with biological tissue to delivery a therapy to the patient. These therapy devices are part of a system that may include signal or implantable pulse generators (IPGs) or drug delivery pumps or combinations of such. The stimulators or pumps in the system may be external to, or implanted in, the patient.
Medical electrical leads may be used, for example, to delivery electrical energy to various biological tissues such as the heart, brain, or peripheral nervous system, etc. For example, implantable leads, such as the Medtronic Model 3487A lead, have been used for stimulating the dorsal columns of the spinal cord, or implantable leads, such as the Medtronic Model 3587A, have been used for peripheral nerve stimulation.
Medical drug delivery catheters, for example, may be used to delivery therapeutic agents to the intrathecal space of the spinal canal, or to the blood vasculature, or brain ventricles, etc. Catheters such as the Medtronic Model 8703 may be used for these types of applications.
Retention devices, typically referred to as anchors, are utilized to secure these leads and catheters thereby prevent lead or catheter movement or migrations. U.S. Pat. No. 5,843,146, which is assigned to Medtronic, discloses a medical lead anchor for anchoring a medical lead relative to, for example, the epidural space of the spinal cord.
Another such anchor is the Medtronic Model 3550 EZ Anchor. This anchor consisted of a molded elastomer, e.g., medical grade silicone rubber, suitable for long-term implantation into a patient. The surface of the Model 3550 EZ Anchor is covered with a pattern of bumps. The bumps allow sutures to be placed in a constricting manner around the midportion of the anchor.
Yet another example is U.S. Pat. No. 4,553,961 (Pohndorf et al), which is entitled “suture sleeve with structure for enhancing pacing lead gripping.” One of the embodiments of the suture sleeve of the Pohndorf et al '961 patent includes a gripping enhancing structure, which comprises a framework of an undulating or sinuous, continuous rib including axially extending segments, or simply axial segments, and short partially circular segments, or simply short circular segments. Each short circular segment connects an adjacent pair of axial segments at one end of the framework. Each axial segment of the sinuous rib is spaced an equal distance from each of the adjacent axial segments and this formation purportedly allows for compressibility of framework against a lead body. The short circular segments of the Pohndorf et al '961 patent are shown as being at the same radial distance or position relative to the through-bore of the suture sleeve.